- FEV1 values must be ≥60% of predicted normal values following a 6 hour albuterol withhold, and reversibility of FEV1 of at least 12% (equal to or greater than 200 cc) following up to four puffs of albuterol must occur; or asthma physician at study site must state based on medical history, exam, and spirometry data that patient has presumptive mild-moderate persistent asthma.